1. Field of the Invention
This invention relates to a material for forming a very fine pattern used for fabricating semiconductor devices, and a method of producing such a material.
2. Description of the Related Art
With the appearance emergence of higher integration and miniaturization in electronic devices in recent years, a fine etching technique for use at sizes in the order of below half a micron has been required. In the field of photolithography, a shift has already occurred to using a short wavelength exposure light source so as to satisfy this requirement, and a resist material adaptable to such novel lithographic technique has been required.
Conventional photoresists to cope with UV (ultraviolet light) exposure primarily use a novolak resin as the base, but since absorption in the far UV region, is high, pattern accuracy capable of coping with miniaturization cannot be obtained. To solve this problem, a chemical amplification type resist, which needs a smaller amount of a photosensitive agent, has been developed. Such a resist predominantly uses polyvinylphenol as a base.
In such a chemical amplification resist according to the prior art, however, an acid generated by exposure is neutralized by an amine, etc., contained in the environmental atmosphere and catalytic activity is lost. Further, diffusion of the acid occurs in the resist layer, and it becomes difficult to obtain a desired pattern. This means that the chemical amplification resist according to the prior art cannot be easily applied to a mass-production process.
If a coating film is applied to the resist surface to protect the resist layer from external air, inactivation of the acid due to contact with external air can be prevented. However, this method cannot prevent diffusion of the acid inside the resist layer, so that dimensional accuracy of a pattern cannot be retained.